It is shown in West German Offenlegungsschrift No. 2,307,248 that derivatives of 4-nitro diphenylether have an excellent acaricidal activity. The derivatives of diphenylether of the present invention have no nitro substituent on the phenyl ring and yet have an acaricidal activity superior to that of said derivatives of 4-nitro diphenyl ether. Furthermore the compounds of the present invention have an excellent residual efficacy.